Bis‐Alkoxide Dysprosium(III) Crown Ether Complexes Exhibit Tunable Air Stability and Record Energy Barrier

Abstract High‐performance and air‐stable single‐molecule magnets (SMMs) can offer great convenience for the fabrication of information storage devices. However, the controversial requisition of high stability and magnetic axiality is hard to balance for lanthanide‐based SMMs. Here, a family of dysprosium(III) crown ether complexes possessing hexagonal‐bipyramidal (pseudo‐D6h symmetry) local coordination geometry with tunable air stability and effective energy barrier for magnetization reversal (U eff) are shown. The three complexes share the common formula of [Dy(18‐C‐6)L2][I3] (18‐C‐6 = 1,4,7,10,13,16‐hexaoxacyclooctadecane; L = I, 1; L = OtBu 2 and L = 1‐AdO 3). 1 is highly unstable in the air. 2 can survive in the air for a few minutes, while 3 remains unchanged in the air for more than 1 week. This is roughly in accordance with the percentage of buried volumes of the axial ligands. More strikingly, 2 and 3 show progressive enhancement of U eff and 3 exhibits a record high U eff of 2427(19) K, which significantly contributes to the 100 s blocking temperature up to 11 K for Yttrium‐diluted sample, setting a new benchmark for solid‐state air‐stable SMMs.


Figure S27
. Plot of magnetization decay vs. time used to extract relaxation times τ for 2@Y at 2, 3, 5, 7, 9, 10 and 11 K. Red line represents the fits to the data using the equation where M0 is the initial magnetization after zero external field was achieved.
Table S18.Parameters used to fit dc magnetic relaxation data for 2@Y and magnetic relaxation times extracted from these fits.Table S19.Parameters used to fit dc magnetic relaxation data for 3@Y and magnetic relaxation times extracted from these fits.

Figure S4 .
Figure S4.Infrared spectrum of 2 over time in air atmosphere.

Figure S5 .
Figure S5.Infrared spectrum of 3 over time in air atmosphere.

Figure S8 .
Figure S8.Photographs of single-crystal samples of 2(a-c) and 3(d-f) exposed to air over time.

Figure S9 .
Figure S9.(a) Temperature-dependence of the DC magnetic susceptibility of 1 under an applied DC field of 1000 Oe.(b) Field-dependence of the magnetization of 1 at 2 K.The solid line is guide for the eyes.

Figure S10 .
Figure S10.(a) Temperature-dependence of the DC magnetic susceptibility of 2 under an applied DC field of 1000 Oe.(b) Field-dependence of the magnetization of 2 at 2 K.The solid line is guide for the eyes.

Figure S11 .
Figure S11.(a) Temperature-dependence of the DC magnetic susceptibility of 3 under an applied DC field of 1000 Oe.(b) Field-dependence of the magnetization of 3 at 2 K.The solid line is guide for the eyes.

Figure S12 .
Figure S12.Temperature dependence of the in-phase (χ', top) and out-of-phase (χ'', bottom) ac susceptibility for 1 in a zero DC field with an AC frequency of 1 and 1218 Hz.

Figure S13 .
Figure S13.Temperature dependence of the in-phase (χ', top) and out-of-phase (χ'', bottom) AC susceptibility for 2 (a) and 2@Y (b) in a zero DC field with an AC frequency of 1-1218 Hz.

Figure S14 .
Figure S14.Temperature dependence of the in-phase (χ', top) and out-of-phase (χ'', bottom) AC susceptibility for 3 (a) and 3@Y (b) in a zero DC field with an AC frequency of 1-1218 Hz.

Figure S15 .
Figure S15.Frequency-dependence of the in-phase (χ', top) and out-of-phase (χ'', bottom) AC susceptibility for 2 (a) and 2@Y (b) under zero DC field and an oscillating field of 3.5 Oe with ac frequencies of 1-1218 Hz from 42 to 141 K.The solid lines are best fits with Debye model.

Figure S16 .
Figure S16.Frequency-dependence of the in-phase (χ', top) and out-of-phase (χ'', bottom) AC susceptibility for 3 (a) and 3@Y (b) under zero DC field and an oscillating field of 3.5 Oe with ac frequencies of 1-1218 Hz from 48 to 150 K.The solid lines are best fits with Debye model.

Figure S17 .
Figure S17.Cole-Cole plots for the ac susceptibilities in zero DC field for 2 (a) and 2@Y (b) from 42 to 141 K.The solid lines are best fits with Debye model.

Figure S18 .
Figure S18.Cole-Cole plots for the ac susceptibilities in zero DC field for 3 (a) and 3@Y (b) from 48 to 150 K.The solid lines are best fits with Debye model.

Figure S19 .
Figure S19.Temperature dependence of the out-of-phase (χ'') ac susceptibility for after one day of exposure to air in a zero DC field with selected AC frequencies of 10 Hz and Hz.

Figure S20 .
Figure S20.Temperature dependence of the out-of-phase (χ'') ac susceptibility for after one week of exposure to air in a zero DC field with selected AC frequencies of 10 Hz and 1030 Hz.

Figure S21 .
Figure S21.Field-cooled (FC, red) in cool mode from 30 to 2 K and zero-field-cooled (ZFC, blue) in warm mode from 2 to 30 K magnetic susceptibility for 2 (a) and 2@Y (b) under an applied DC field of 2000 Oe.

Figure S22 .
Figure S22.Field-cooled (FC, red) in cool mode from 30 to 2 K and zero-field-cooled (ZFC, blue) in warm mode from 2 to 30 K magnetic susceptibility for 3 (a) and 3@Y (b) under an applied DC field of 2000 Oe.

Figure S23 .
Figure S23.Magnetic hysteresis loops for 2 (a) and 2@Y (b).The data were collected at temperature range of 2 to 12 K with an average sweep rate of 15 Oe s -1 .

Figure S24 .
Figure S24.Magnetic hysteresis loops for 3 (a) and 3@Y (b).The data were collected at temperature range of 2 to 14 K with an average sweep rate of 15 Oe s -1 .

Figure S25 .
Figure S25.Magnetic hysteresis loops of 2 measured after one day of exposure to air.The data were collected at 2 K with an average sweep rate of 15 Oe s -1 .

Figure S26 .
Figure S26.Magnetic hysteresis loops of 3 measured immediately (red) and after one week of exposure to air (dark blue).The data were collected at 2 K with an average sweep rate of 15 Oe s -1 .

Table S2 .
Crystal data and structure refinement for 3 and 3Y.

Table S10 .
Continuous Shape Measures (CShM) calculations for the potential coordination geometries of 1-3.The lowest CShMs value is highlighted.

Table S13 .
Relaxation fitting parameters of a generalized Debye model for 2.

Table S14 .
Relaxation fitting parameters of a generalized Debye model for 2@Y.

Table S15 .
Relaxation fitting parameters of a generalized Debye model for 3.

Table S16 .
Relaxation fitting parameters of a generalized Debye model for 3@Y.

Table S22 .
Ab initio calculated crystal field parameters for Dy(III) ion in 2.

Table S23 .
Average transition magnetic moment elements between the states in 2, given in μB

Table S24 .
Ab initio calculated crystal field parameters for Dy(III) ion in 3.

Table S25 .
Average transition magnetic moment elements between the states in 3, given in μB.